The technology relates to an automatic transmission that utilizes a shift-by-wire system in which shift ranges are automatically switched with use of an actuator. In particular, the technology relates to a shift-by-wire control device that compulsorily switches any shift range to a parking range in response to a state of a vehicle.
A vehicle automatic transmission may utilize a shift-by-wire system in which shift ranges may be automatically switched with use of an electric actuator such as a solenoid. Non-limiting examples of the shift ranges may include a drive (D) range, a reverse (R) range, a neutral (N) range, and a parking (P) range. For such an automatic transmission, for purpose of improving safety, an auto parking control technique is known that involves compulsorily switching any shift range to the parking range, on a condition that the shift range is set to other than the parking range when a driver stops a vehicle and leaves the vehicle.
For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2013-199963 discloses a technique in which any shift range is compulsorily switched to the parking range by determining that a vehicle is in preparation for stopping, on conditions that opening of a door at a driver's seat is detected and an unfastened state of a seat belt of a driver is detected. JP-A No. 2003-156140 discloses a technique in which any shift range of a vehicle is compulsorily shifted to the parking range, on a condition that driver's action of leaving a vehicle is detected, for example. For purposes of preventing erroneous operation and improving safety, JP-A No. 2007-170546 discloses a technique in which any shift range is switched to the parking range, on conditions that a vehicle speed is less than a predetermined speed, an unfastened state of a seat belt by a driver is detected, and a load applied onto a driver's seat is equal to or less than a predetermined value, for example.